1. Field of the Invention
The present invention relates to an ignition distributor for an internal combustion engine, and more particularly to an ignition distributor of the type which includes a distributor rotor coaxially fixed to an end portion of a camshaft extending outwardly from a cylinder head of the engine.
2. Description of the Prior Art
In Japanese Patent Early Publication Nos. 58-176471 and 61-1872, there has been proposed an ignition distributor whose housing is composed of a distributor housing and of a distributor cap fixedly coupled thereon, wherein the distributor housing is fastened to an engine block to cover a timing belt stretched over a driven pully mounted on an end portion of a camshaft extending outwardly from the engine block, the distributor housing having an end wall formed therein with a circular opening through which a distributor rotor is inserted and fixed to the end portion of the camshaft coaxially therewith, and wherein the distributor cap is detachably coupled with the end wall of the distributor housing to cover the distributor rotor. In such an arrangement of the ignition distributor, an annular space around the distributor rotor is formed as narrow as possible to protect the timing belt from ozone gas entering into the distributor housing from the rotor space and to protect the distributor rotor from dust particles entering into the rotor space from the distributor housing. However, the annular space is in a simple form. For this reason, it is difficult to prevent the entry of ozone gas into the distributor housing or the entry of dust particles into the rotor space. In an attempt to solve the problem, it has been proposed to dispose a seal member in the annular space. In such a case, the assembly of the distributor rotor with the camshaft becomes difficult due to the presence of the seal member.